This invention relates generally to the art of resuscitation equipment and more particularly to an apparatus which actuates a demand valve assembly used to regulate breathing or resuscitation equipment.
In emergency medical situations, the condition of a patient frequently requires that rescuers perform several life-saving procedures concurrently, including cardiopulmonary resuscitation (CPR), the control of hemorrhaging, administration of drug therapy, interpretation of EKG, etc. Performance of each individaul task must be properly and efficiently executed in order to provide timely benefit to the patient. There are severe limitations, however, which must be overcome in order to render optimal service.
If a patient requires cardiopulmonary resuscitation, rescuers administer this procedure at once. Effective CPR performed either manually or with mechanical assistance includes both chest compressions to stimulate the patient's heart and ventilation of the patient's lungs. The timing and coordination of the chest compressions with the ventilation of the lungs is critical, and efficient performance is extremely difficult, even by two trained medical technicians, each attending to a different function.
Efficiency is promoted, however, by use of automated CPR apparatus or resuscitators. Use of a resuscitator also typically enables CPR to be performed by a single rescuer, freeing a second rescuer to effect other life-saving measures. Such apparatus may include a means, such as a plunger, for compressing the patient's chest, an airway device comprising of an endotracheal tube, a tracheotomy tube or an air hose and associated mask, or a combination of both.
The prior art provides a variety of devices for mechanically assisting CPR procedures performed by a single rescuer. These devices, comprehensive in scope, include U.S. Pat. No. 4,664,098 to Woudenberg, et al., disclosing a cardiopulmonary resuscitator which performs mechanical CPR while restraining the patient's chest against lateral displacement during the operation of a plunger mechanism.
In U.S. Pat. No. 4,349,015 to Alferness, a manually-actuable CPR apparatus is described, including a bellows on a patient's chest which, when manually compressed, contributes to the increase of the patient's intrathoracic pressure.
A pulmonary resuscitator with electrical control system, described in U. S. Pat. No. 3,333,581 to Robinson, et al., provides for the resuscitation of patients exhibiting breathing difficulties, the operational mode of which may be electrically regulated in accordance with presented needs.
Other related devices are disclosed in U.S. Pat. No. 4,676,232 to Olsson, et. al., and in U.S. Pat. No. 4,620,538 to Koegel, et al.
Additionally, a particular valve assembly is described in U.S. Pat. No. 3,795,257 to Fabish, et al., to be used in conjunction with breathing or resuscitation equipment.
Whereas the aforementioned resuscitators allow CPR administration by a single rescuer and are perhaps more efficient than non-mechanical means in reproducing cardiac and pulmonary functions. They are bulky, cumbersome and expensive. In addition, in the case of a pulmonary resuscitator, its mechanical operation supersedes the patient's own attempts at breathing as well as the need to hyperventilate the patient following transtracheal drug therapy or suctioning. Further, even under optimal conditions, the use of the device challenges the rescuer to time chest compressions for perfect integration with programmed ventilations. Even though a single rescuer can adequately perform CPR with the assistance of a resuscitator, the factors of bulk, size, expense and being inappropriate at well-defined times do not allow resuscitators to be viable options for most emergency services.